Freon wrote:It is theoretical (calculated) rather than just an injector pulse width map. So all factory fuel trims are in place. The VE map is 3D. It seems to work quite well so far, even cold vs warm engine.
Interesting! Willing to post screenshots of the map?
Ideally, a 2D VE map + density calculation would make it a snap to just punch in AFR values and run with it, like the factory mass-airflow system, which I find quite novel coming from the AEM. There isn't really a practical difference between a 3D VE map and a pulsewidth map. If VE is changing with pressure (density), it's because a linear VE calculation isn't detailed enough to consider all factors.
For example at an idle intake manifold pressure of -10psig, the exhaust manifold pressure is at least 0psig. At an intake manifold pressure of 0psig, the exhaust pressure could still be close to 0psig (or maybe not at high RPM). At +20psig intake, the exhaust manifold pressure is almost certainly very high -- +20psig or more -- and could double from low to high RPM. Since we only have access to intake MAP and not exhaust manifold pressure, we can't build a model formula that "knows" how much air is passing through the engine -- never mind the fact that we'd have a hard time quantifying an engine's sensitivity to exhaust pressure.
Not knocking what you're doing, I just wanted to open a discussion on fueling methods. The simplest way IMO is just to 3D map the entire engine and forget about "VE", which is a useful concept to understand cylinder filling but is of relatively little practical value in engine management. It sounds like what you've done is the same thing, but with different numbers in the boxes. In the end either method ends up being user-transparent; whether the number in the box is called "VE", "pulsewidth", or "raw", the map looks the same.
EDIT: I suppose you could have two 3D maps (which is redundant and confusing): one VE map, and the other an AFR map. Increasing one cell and decreasing the corresponding cell on the other map would cancel each other out. This philosophy might be an extension of the ideal where the factory management is measuring total air mass into the system and can easily calculate how much fuel to balance it to a specific AFR (novel to me, having had no experience with that before).
Much easier just to have one map.
-Chris